Application to determine reading/working distance

ABSTRACT

A method of measuring working distance between a handheld digital device and eyes of a user, including capturing an image of at least eyes of a user via an onboard camera of the handheld digital device while the user is viewing a display of the handheld digital device and comparing an apparent angular size of a structure of the eyes or face of the user to a previously captured image of the structure of the eyes or the face that was taken in the presence of an object of known size. The method further includes calculating a working distance based on the apparent angular size of the structure of the eyes or the face; and saving at least the working distance to memory or reporting out the calculated working distance on the display. A handheld digital device programmed with an algorithm to perform the method is also included.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. ProvisionalApplication No. 62/529,530, filed Jul. 7, 2017, entitled “Application toDetermine Reading/Working Distance”, and U.S. Provisional ApplicationNo. 62/563,879, filed Sep. 27, 2017, entitled “Application to DetermineReading/Working Distance,” both of which are hereby incorporated intheir entirety by reference.

TECHNICAL FIELD

Embodiments of the invention generally relate to the field of measuringdistances in the context of eye care. More particularly, embodiments ofthe invention relate to monitoring reading ability of eye care patients.

BACKGROUND

Near working distance is a measurement from the eyes of an individual tomaterial that they are reading or viewing at near distances. It comesinto play, for example, in the context of reading a book, a newspaper orthe screen of a handheld digital device. For example, near workingdistance is commonly measured in a clinical circumstance by asking apatient to hold in their hand and read a near point card which has on itprinted letters of known sizes and requiring known visual acuity.

Measurement of near working distance and near visual acuity can providevaluable information that is useful in determining how effectively anindividual is able to focus on and read printed material or view otherimages. Near working distance can give an indication of how successfullyan individual is able to read or perceive materials viewed at near.

Personal computers and handheld digital devices are more and more oftenused for the reading of materials instead of conventional materialsprinted on paper. It is also the case that many personal computers andhandheld digital devices such as smart phones, tablets, laptop computersand desktop computers now include a camera as part of their structure.Many of the cameras that are present include some form of autofocusmechanism and are capable of capturing both still and moving images.

Accommodation is the act of focusing from distance to near. In youthaccommodation is very flexible and permits individuals to focus on nearobjects with minimal effort. Generally accommodation happens soautomatically that people are entirely unaware of it. Conventionalintraocular lens implants are generally provided in a prescription thatfocuses the patient's eye for clear distance vision. Generally readingglasses or other lenses are then used for near vision. While alternativeapproaches such as the monovision technique are available they are lessthan ideal and are successful only for some patients.

Intraocular lens implants that are utilized to provide correctivefocusing after the natural lens is removed during cataract surgery nowoften include so-called accommodating or near vision intraocular lensimplants. Through a variety of mechanisms these implants seek to provideassistance to patients when shifting vision from distance to near thatattempt to emulate the natural focusing mechanism that exists in theyouthful eye.

Accordingly there is still room for improvement in the eye care arts asto measuring working distance in real-life situations.

SUMMARY

Embodiments of the invention assist in providing useful clinicalinformation to eye care practitioners by providing a way ofunobtrusively monitoring the near working distance that a patient isactually using and providing information to the eye care practitioner bya variety of communication options.

An example embodiment of the invention includes a method of measuringworking distance including calibrating by capturing an image of a user'sface with an object of known size. The method further includes utilizingthe known size of the object to calculate a relative size of structuresof the face or eyes. The method also includes utilizing the known sizeof the object to calculate a distance between the camera of the handhelddigital device and the patient eyes based on the known size of theobject.

The example method also includes utilizing the calculated size of thestructures of the face or eyes to determine a distance between thecamera of the handheld digital device and the eyes of the patient whilethe patient is reading or viewing materials that are displayed on thehandheld digital device. The method further includes monitoring theletter size of materials read on the handheld digital device display andincludes storing in memory the calculated working distance along withthe letter size of the materials read in a memory.

According to another example embodiment, the method further includestransmitting data to the health care professional from the handhelddigital device including the working distance and letter size of thematerials read. The method may also include calculating Snellen acuityor another acuity equivalent based on the working distance and the sizeof the materials read. Snellen acuity in this context is expected to beapproximate as normal reading fonts do not necessarily comply with theSnellen equivalent for visual acuity. The method may also includetransmitting the Snellen acuity and working distance to the health carepractitioner for review.

The method according to an example embodiment of the invention may alsoinclude identifying from a captured image whether the user is wearingglasses or not when viewing the display on the handheld digital device.This information may be recorded and/or transmitted to the health carepractitioner.

A handheld digital device according to example embodiments of theinvention includes, for example, a smart phone or a tablet. Embodimentsthe invention may also utilize a laptop computer or desktop computer.

A handheld digital device according to an example embodiment of theinvention generally includes a display, a camera module, a processor anda memory.

According to another example embodiment of the invention the processorof the handheld device is programmed with an algorithm that includes animage capture engine and an image analysis engine. The image captureengine includes computer code to be run by the processor that capturesimages for calibration and also captures images for measurement via acamera that is incorporated into the digital device.

The image analysis engine functions to analyze captured images both forthe purposes of calibration and the purposes of measurement as well asanalyzing images, for example, to determine whether glasses are worn atthe time of reading.

According to another example embodiment, in the context of calibrationan image is captured by the image capture engine of the face and eyes ofa user along with an object of known size. For example, a credit cardmay be held in front of the forehead of the user since a credit card isof a known and standardized size. Another object of standardized sizecan be utilized as well. The image analysis engine is utilized toidentify the object of known and standardized size as well as toidentify structures of the face and/or eyes of the user in the captureddigital image. For example, the white to white distance of one or botheyes can be used. The white to white distance is commonly understood tobe analogous to the horizontal visible iris diameter (HVID). That is thedistance across the cornea and iris and between the sclera of the eye oneither side of the cornea.

The image analysis engine, according to an example embodiment furthercomprises a calculation engine that mathematically compares the apparentsize of the known object to the apparent size of the white to whitedistance in the digital image to determine the white to white distanceof one or both eyes. The white to white distance is then available foruse to calculate the working distance between the handheld device andthe eye at any given time because the apparent angular size of the whiteto white distance as captured by an image from the camera of thehandheld device will vary depending upon the working distance betweenthe device and the eye. White to white distance is used as an examplehere but should not be considered limiting. Other eye or facialstructures may be utilized as well.

In the context of measurement, an image is captured of the eye andfacial structures while the user is viewing or reading material on thedisplay of the handheld device. According to an example embodiment ofthe invention, the image analysis engine determines the apparent angularsize of the eye or facial structures, for example, the white to whitedistance of one or both eyes. The image analysis engine then cancalculate the working distance between the handheld device and the eyesbased on the apparent size of the structures in the captured image.

Optionally, according to an example embodiment, the image analysisengine can analyze the image displayed on the display of the handhelddevice to determine the font size of letters that are presented on thedisplay. With the known working distance and the known font size ofletters the image analysis engine can then calculate the visual acuityassociated with the working distance and the letter size. Thedetermination of visual acuity is based on the angular size of lettersread and can be correlated to Snellen visual acuity which is known tothose of skill in the art. Further for example, the image analysisengine can analyze the brightness of the image displayed on the displayof the handheld device, the ambient brightness of ambient light or acombination of both.

The image analysis engine then can store the working distance along withidentifying factors such as time and date in a memory the handhelddevice. Alternately, the image analysis engine can store the Snellenvisual acuity along with identifying factors such as time, date and evenlocation. The image analysis engine may also determine and record someindication of ambient lighting conditions at the time of reading andimage capture as well as brightness of the display at the time ofreading and image capture. Ambient light and brightness of the displaymay both affect the near vision function.

According to another example embodiment, stored measurements can betransmitted to a health care professional via the Internet, via wiredconnection or wireless connection. Alternately, measurements can betransmitted as soon as they are made.

A number of eye related circumstances present situations that may makeit valuable to track working distance as an indication of near visionfunction. For example, such information may be valuable in patientsutilizing monovision and patients who have undergone LASIK or otherrefractive surgery as well as patients with corneal inlays to assistwith near vision. Further, it may be useful to track near vision in anormal patient approaching presbyopia and to provide information as tothe onset of near focusing difficulties. Application of variousembodiments of the invention may be utilized, for example, for patientswho are approaching presbyopia to monitor their working distance andnear vision status. Embodiments of the invention function to notify asurgeon or another eye care practitioner that working distance isincreasing for the patient and, therefore, the patient may be needingassistance for near focusing because of presbyopia.

According to a further example embodiment, the handheld digital devicecan present a moving image similar to that of an optokinetic drum oroptokinetic tape. These devices present a moving image of stripes, barsor checker boards that elicit optokinetic nystagmus in normallyresponsive eyes and visual systems. The evaluation of optokineticnystagmus is useful for evaluation of neurological, otological orophthalmological disorders. This embodiment may also include the imageanalysis engine tracking of eye movements in response to the optokineticstimulus as well as saving of this information and transmission of thisinformation to a health care practitioner. According to embodiments ofthe invention, the device can be adapted to present the optokineticstimulus from left to right, right to left, top to bottom or bottom totop. Alternately, the device can be adapted to present the optokineticstimulus in a single direction and provide instructions to the user toorient the handheld digital device in and appropriate orientation todirect the stimulus as desired. As a complement to the other near visionassessment performed by the device, the optokinetic stimuli may bepresented with different bar widths and spacing to assist in evaluationof near visual acuity and near visual function.

According to another example embodiment, distance from the handhelddigital device to the eye is measured by a depth mapping process usingprojected patterns. According to this example embodiment, a method formapping includes projecting a pattern of multiple spots onto the face ofthe viewer. The multiple spots have respective positions and shapes andthe positions of the spots in the pattern are uncorrelated, while theshapes share a common characteristic. Information about the size andspatial distortion of the multiple spots is gathered and used togetherto determine information about the depth or distance between the cameraof the handheld digital device and the face. An image of the spots onthe face is captured and processed so as to derive a three-dimensionalmap of the face from which a depth or distance to the eyes can bedetermined. According to this example embodiment the projected patternmay include a laser speckle pattern. According to this technique, apixel image includes pixels that represent a depth or distance betweenthe handheld digital device and the face rather than brightness orcolor. Application of this example embodiment takes advantage ofhardware and software incorporated into at least some handheld digitaldevices that is also used for facial recognition.

According to another example embodiment of the invention, a depth map iscreated of the scene containing a face of a human user of the handhelddigital device. The depth map includes a matrix of pixels. Each pixelcorresponds to respective location in the scene and includes arespective pixel value indicative of a distance from a referencelocation at the handheld digital device to the respective location ofthe pixel. The depth map can be segmented to identify a contour of theface representing the eyes or bridge of the nose which can then beprocessed to identify the eyes or the bridge of the nose to identify adistance between the eyes or the bridge of the nose and the handhelddigital device. Information related to such an embodiment can be foundin U.S. Pat. No. 8,249,334 as well as U.S. Pat. No. 8,050 461, each ofwhich is incorporated herein by reference.

According to another embodiment of the invention, the handheld digitaldevice may include an apparatus for 3-D mapping of the face thatincludes an illumination assembly having a coherent light source and thediffuser which are arranged to project a speckle pattern on the face.Then, a single image capture assembly, such as the selfie, the camera ona cell phone or other handheld digital device can capture images of theprimary speckle pattern with an infrared sensor from a single, fixedlocation and at a known angular position relative to the illuminationsource. The processor of the handheld digital device is programmed withan algorithm to process images of the speckle pattern to derive a 3-Ddepth map of the face. This then can be utilized to identify thedistance between the handheld digital device and desired structures ofthe face such as the eyes or the bridge of the nose. Aspects of such adevice are described in U.S. Pat. No. 8,390,821 which is incorporatedherein by reference.

According to another example embodiment, a handheld digital deviceincludes an illumination unit and an imaging unit. The illumination unitis structured to emit coherent light and to generate a random specklepattern that is projected onto the face of the user of the handhelddigital device. The imaging unit captures image data related to the faceof the user and the random speckle pattern. The image data then is usedto identify desired structures of the face such as the eyes or thebridge of the nose and to determine a distance between the handhelddigital device and the structures. This then, enables determination ofthe working distance between the handheld digital device and the user'seyes.

The data processor of the handheld digital device may include a firstinput port the receives color image data and thus including a firstarray of color image pixels from the first image sensor as well as asecond input port that receives depth related image data from a secondimage sensor as well as processing circuitry that generates a depth mapusing the depth related image data. The depth map can be furtherprocessed to identify structures of the eyes or bridge of the nose ofthe face and to determine a working distance between the handhelddigital device and the eyes or bridge of the nose of the user. U.S. Pat.No. 8,456,517 which is incorporated by reference herein describesaspects of such a device.

According to another embodiment, the handheld digital device may performa method of processing data including receiving a temporal sequence ofdepth maps of the scene including the face and using at least one of thedepth maps to determine the location of the eyes or bridge of the noseand estimating distance between the handheld digital device and the eyesor the bridge of the nose. U.S. Pat. No. 8,565,479 is incorporatedherein by reference.

According to another embodiment, the handheld digital deviceincorporates an illumination assembly that projects a speckle pattern ofmonochromatic light, for example, in the infrared wavelengths on to theface of a user. A processor of the handheld digital device is configuredand adapted to process signals to generate an output a depth map of theface which then can be used to identify the eyes or bridge of the nosein order to determine a working distance between the handheld digitaldevice and the user's eyes.

The following United States patents relate to embodiments of theinvention and are hereby incorporated by reference. U.S. Pat. Nos.8,582,867; 8,594,425; 8,717,417; and 8,749,796; 8,781,217; 8,786,682;8,787, 663; 8,824,737; 8,824,781; 8,848,039; and 8,872,762.

The above summary is not intended to describe each illustratedembodiment or every implementation of the subject matter hereof. Thefigures and the detailed description that follow more particularlyexemplify various embodiments.

The above summary is not intended to describe each illustratedembodiment or every implementation of the subject matter hereof. Thefigures and the detailed description that follow more particularlyexemplify various embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

Subject matter hereof may be more completely understood in considerationof the following detailed description of various embodiments inconnection with the accompanying figures, in which:

FIG. 1 is a schematic depiction of a digital handheld device and useraccording to an example embodiment of the invention;

FIG. 2 is a schematic depiction of angular size is related to visualacuity according to the prior art;

FIG. 3 is a schematic block diagram of a handheld digital deviceaccording to an example embodiment of the invention; and

FIG. 4 is a flowchart depicting a method according to an exampleembodiment of the invention.

While various embodiments are amenable to various modifications andalternative forms, specifics thereof have been shown by way of examplein the drawings and will be described in detail. It should beunderstood, however, that the intention is not to limit the claimedinventions to the particular embodiments described. On the contrary, theintention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the subject matter as defined bythe claims.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to FIGS. 1-4, example embodiments of the invention generallyinclude a handheld digital device 10 programmed with an algorithm foruse of the invention, and a method of measuring working distance betweenthe handheld digital device and the eyes of a user viewing the device.

Referring particularly to FIG. 3, handheld digital device 10 generallyincludes processor 12, memory 14, display 16 and camera 18. Generally,processor 12 and memory 14 are provided within body 20 of handhelddevice digital device 10. Display 16 generally appears on at least oneouter surface of handheld digital device 10. Many handheld digitaldevices 10 include camera 18 that faces a user when the user is viewingdisplay 16. Thus, camera 18 permits the capturing of an image of theuser while the user is viewing the display 16.

Referring particularly to FIG. 1, handheld digital device 10 is held atworking distance 22 from patient's face 24 and eyes 26 when in use. Forexample, when reading text on display 16 of handheld digital device 10working distance 22 is generally considered to be the distance of fromdisplay 16 to the anterior surface of eyes 26. Working distance 22varies dependent upon many factors including an individual's arm lengthand ability to focus on near objects. Generally, most individuals willincrease working distance 22 when they are having difficulty reachingdue to limitations of accommodation. Field-of-view 28 of camera 18,according to an example embodiment, includes eyes 26 and at least partof face 24. Object of known size 30 can be presented within field ofview 28 to be captured in an image by camera 18 along with at least partof face 24 and eyes 26. Object of known size 30 can include, forexample, a credit card or other readily available object that has aknown and standardized size.

Referring particularly to FIG. 2, visual acuity, as known in the priorart relates to apparent angular size 32 of a viewed object, in this caseletter 34 at eye 26. As can be seen by reference to FIG. 2 and as isknown to those skilled in the art, readability of text depends both on asize of letter 34 and working distance 22 from eye 26 to letter 34.

According to another example embodiment of the invention, camera 18includes an autofocus mechanism which as part of its autofocus functiondetermines a distance from camera 18 to an object to be photographed, inthis case eyes 26. In this example embodiment, working distance 22 canbe determined directly from the autofocus measured distance.

According to another example embodiment of the invention, a method ofdetermining working distance 22 between a digital device 10 and eyes 26is utilized. According to the example method, as depicted in the flowchart of FIG. 4, object of known size 30 is placed in front of or nearface 24. Notably, object of known size 30 is not placed in front of eyes26.

Processor 12 of digital device 10 comprises image capture engine 36 andimage analysis engine 38. Image capture engine 36 is programmed with analgorithm to perform image capture functions discussed herein. Imageanalysis engine 38 is programmed with an algorithm to perform imageanalysis and calculation functions as described herein. Image captureengine 36 and image analysis engine 38 together function to perform themethods according to embodiments of the invention.

An example embodiment includes placing object of known size 30 in frontof or near face 24 for calibration. The method further includescapturing an image of eyes 26 and/or face 24 as well as object of knownsize 30 with camera 18 of handheld digital device 10 by application ofimage capture engine 36. Image analysis engine 38 is then utilized toanalyze features of the captured image. The relative size of ocular orfacial structures is determined relative to the object of known size 30.For example the white to white distance of the eye can be determined.Also, working distance 22 between camera 18 and object of known size 30can be determined by geometric calculation based on the apparent angularsize of object of known size 30. Such geometric calculations are knownin the field of geometric optics. Thus, based on future image capturesworking distance 22 can be calculated by image analysis engine 38 basedon apparent angular size 32 of ocular structures, such as eyes 26, incaptured images. This completes the calibration of image analysis engine38 as regards working distance and apparent angular size 32 of structureof eyes 26.

Handheld digital device 10 is commonly used to read or view text such asnews reports, blogs, email messages and text messages. Exampleembodiments of the invention are utilized to measure working distance 22between handheld digital device 10 and eyes 26. Working distance 22utilized by an individual provides an indication of how successfully andcomfortably a user is able to read text on display 16 of handhelddigital device 10. If a user is capable of reading displayed text at aworking distance that is typical, for example 40 to 50 cm it wouldgenerally be accepted that the user is functioning well as to nearfocusing. If however, a user finds it necessary to move handheld digitaldevice 10 to a greater working distance, for example 70 cm, it issuggestive that the user is not functioning well as to near focusing.

Accordingly, example embodiments of the invention enable monitoring ofworking distance 22 while the user goes about their normal day-to-daydigital activities using handheld digital device 10. To assist inaccomplishing this image capture engine 36 captures an image of face 24and eyes 26 of a user while the user is reading text displayed ondisplay 16 or viewing other materials on display 16. Monitoring isaccomplished by analyzing a captured image with image analysis engine38. Accordingly, reading material is presented on display 16 of handhelddigital device 10 while image analysis engine 38, optionally, capturesand records a font size of text, if text is displayed.

Image capture engine 36 is then utilized to capture an image of face 24and/or eyes 26 of the user. Image analysis engine 38 is then utilized todetermine the apparent size of structures of face 24 or eyes 26 based onearlier calibration. Based on the apparent size of structures of face 24and/or eyes 26, working distance 22 is calculated by image analysisengine 38. Calculated working distance 22 is then saved to memory 14 byimage analysis engine 38. According to example embodiments of theinvention, other data may be saved to memory 14 as well. For example,time, date, lighting conditions, apparent pupil size and whether theuser is wearing glasses at the time of recording can be captured andsaved. These additional data may be determined from features of handhelddigital device 10 itself in the case of time and date. For other datainformation may be determined by operation of algorithms utilized byimage analysis engine 38, for example, in the case of lightingconditions, ambient brightness, display brightness, apparent pupil sizeand whether the user is wearing glasses.

According to another example embodiment, distance from handheld digitaldevice 10 to eyes 26 can be measured by a depth mapping process usingprojected patterns. According to this example embodiment, a method formapping includes projecting an illuminated pattern of multiple spotsonto face 24 of the viewer. The multiple spots have respective positionsand shapes and positions of the spots in the pattern are uncorrelated,while the shapes share a common characteristic. Information about thesize and spatial distortion of the multiple spots is gathered and usedtogether to determine information about the depth or distance betweencamera 18 of the handheld digital device 10 and face 24. An image of thespots on face 24 is captured and processed so as to derive athree-dimensional map of face 24 from which a depth or distance to eyes26 can be determined. According to this example embodiment, theprojected pattern may include a laser speckle pattern. According to thistechnique a pixel image includes pixels that represent a depth ordistance between handheld digital device 10 and face 24 rather thanbrightness or color. Application of this example embodiment, takesadvantage of facial recognition hardware and software incorporated intoat least some handheld digital devices 10 that is also used for facialrecognition.

According to another example embodiment of the invention, a depth map iscreated of the scene containing face 24 of a human user of handhelddigital device 10. The depth map includes a matrix of pixels. Each pixelcorresponds to respective location on the face or in the scene andincludes a respective pixel value indicative of a distance from areference location at handheld digital device 10 to the respectivelocation of the pixel. The depth map can be segmented to identify acontour of face 24 representing eyes 26 or the bridge of the nose, forexample, which can then be processed to identify eyes 26 or the bridgeof the nose to determine a distance between eyes 24 or the bridge of thenose and handheld digital device 10.

According to another embodiment of the invention, handheld digitaldevice 10 may include an apparatus for 3-D mapping of face 24 thatincludes illumination assembly 40 having coherent light source 42 anddiffuser 44 which are arranged to project an illuminated speckle patternon face 24. Then, a single image capture assembly, such as the selfiecamera 18 on handheld digital device 10 captures images of the primaryspeckle pattern with an infrared sensor from a single, fixed locationand at a known angular position relative to illumination assembly 40.Processor 12 of handheld digital device 10 is programmed with analgorithm to process images of the speckle pattern to derive a 3-D depthmap of face 24. This can be utilized to determine or measure thedistance between handheld digital device 10 and desired structures offace 24 such as eyes 26 or the bridge of the nose.

According to another example embodiment, handheld digital device 10includes illumination assembly 40 and camera 18. Illumination assembly40 is structured to emit coherent light and to generate a random specklepattern that is projected onto face 24 of the user of handheld digitaldevice 10. Image data then can be used to identify desired structures offace 24 such as eyes 26 and to determine a distance between handhelddigital device 10 and eye 26 structures. This then enables determinationof working distance 22 between handheld digital device 10 and user'seyes 26.

Processor 12 of handheld digital device 10 may include a first inputport the receives color image data and thus including a first array ofcolor image pixels from the first image sensor as well as a second inputport that receives depth related image data from a second image sensoras well as processing circuitry that generates a depth map using thedepth related image data. The depth map can be further processed toidentify structures of eyes 26 or face 24 and to determine workingdistance 22 between the handheld digital device 10 and eyes 26 of theuser.

According to another embodiment, handheld digital device 10 may performa computer implemented method of processing data including receiving atemporal sequence of depth maps of the scene including face 24 and usingat least one of the depth maps to determine the location of eyes 26 andestimating distance between handheld digital device 10 and eyes 26.

According to another example embodiment, handheld digital device 10incorporates illumination assembly 40 that projects a speckle pattern ofmonochromatic light, for example, in the infrared wavelengths on to face24 of a user. Processor 12 of handheld digital device 10 is configuredand adapted to process signals to generate and output a depth map offace 24 which then can be used to identify eyes 26 to determine workingdistance 22 between handheld digital device 10 and the user's eyes 26.

According to example embodiments of the invention, data as to workingdistance may be captured periodically or each time handheld digitaldevice 10 is viewed. Alternately, data as to working distance may becaptured based on user activation of the future. Data related to workingdistance 22 is saved in memory 14 for download at the time of a user'snext visit to a health care professional, for example. Alternatively,data related to working distance 22 can be sent via wired or wirelessconnection or via Internet connection to health care professionalperiodically.

According to another example embodiment of the invention, image analysisengine 38 can convert font size and measured working distance to Snellenvisual acuity by calculations that are known to those skilled in theart. This information may also be later downloaded or periodicallytransmitted to a health care professional for analysis.

According to another example embodiment, image analysis engine 38 candetermine and save data related to pupil size during the act of readingby a user. Pupil size may be recorded in correlation with workingdistance and/or font size and/or approximated Snellen visual acuity.

According to a further example embodiment, the handheld digital device10 can present a moving image similar to that of an optokinetic drum oroptokinetic tape on display 16. The moving image of stripes, bars orchecker boards should elicit optokinetic nystagmus in normallyresponsive eyes and visual systems. The evaluation of optokineticnystagmus is useful for evaluation of neurological, otological orophthalmological disorders.

This embodiment may also include capturing of moving images of the eyesand any resulting optokinetic nystagmus and image analysis engine 38tracking and analysis of eye movements in response to optokineticstimulus as well as saving of this information to memory 14 andoptionally, transmitting of this information to a health carepractitioner.

According to embodiments of the invention, the handheld digital device10 can be adapted to present the optokinetic stimulus on display 16 fromleft to right, right to left, top to bottom or bottom to top. Diagonalpresentations can be presented as well. Alternately, handheld digitaldevice 10 is adapted to present the optokinetic stimulus in a singledirection and provide instructions to the user to orient handhelddigital device 10 in an appropriate orientation to direct the stimulusas desired. As a complement to the other near vision assessmentperformed by the device, optokinetic stimuli may be presented withdifferent bar widths and spacing to assist in evaluation of near visualacuity and near visual function.

Referring particularly to FIG. 4, according to an example embodiment ofa method calibration can be accomplished by capturing an image of an eyestructures and/or facial structures including an object of known size inthe image S1. Image analysis engine 38 can then be utilized to determinea size of ocular or facial structures of eyes 26 and/or face 24 relativeto object of known size 30 S2. Working distance 22 may then bedetermined on the basis of object of known size S3. Calibration of themethod is then complete.

Measurement can then proceed by presenting reading materials on adisplay 16 of handheld digital device 10 which are read by a user S4.Optionally, as part of S4 font size presented on the display can bedetermined and recorded. Image analysis engine can then determineworking distance 22 from handheld digital device 10 to eyes 26 based onthe previously determined size of the eye structures or facialstructures of eyes 26 or face 24 S5. Image analysis engine 38 can thensave working distance 22 and if recorded font size in memory 14 S6.

Optionally, image analysis engine 38 can transmit working distance 22and font size if recorded to health care practitioner S7.

Further optionally, according to another example embodiment of themethod, image analysis engine 38 may analyze a captured image todetermine if glasses are worn on the face of a user S8. Image analysisengine 38 may then saved in memory 14 a status as to whether glasses areworn S9. Optionally, status or information as to whether glasses areworn can be transmitted to a health care practitioner via wired orwireless connection or Internet S10.

Further optionally, according to another example embodiment of themethod, image analysis engine 38 may analyze a captured image todetermine a pupil size S11. Image analysis engine 38 may further saveinformation as to pupil size to memory and transmit information as topupil size to a health care practitioner S12.

Further optionally, according to another example embodiment, anoptokinetic image of moving bars stripes or a checkerboard maypre-presented on display 16 of handheld digital device 10. Image captureengine 36 then captures moving images of eye movements that occur inresponse to the optokinetic stimulus S14.

Optionally, image analysis engine 38 may analyze the moving image of eyemovements in response to the optokinetic stimulus to determine whetherthe response is within normal limits S15.

Optionally, image analysis engine 38 may save the moving image of eyemovements and/or the analysis of eye movements to memory 14 S16.

Further optionally, an example embodiment of the method may includetransmitting the moving image of eye movements and/or analysis to ahealth care practitioner S17.

Further, according to another example embodiment of the method, imageanalysis engine 38 may analyze pupil size at various times during theact of reading. Pupil size may be correlated with working distanceand/or font size and/or approximate Snellen visual acuity. Pupil sizeand its correlation with the above factors may assist in determining howwell a particular treatment for presbyopia is working. It may bebeneficial for the health care practitioner to know whether thetreatment is working better when the pupil size is large or when thepupil size is small. Pupil size may also provide some indication ofaccommodative effort as it is known to those skilled in the art thatpupil size may vary with accommodative effort. Generally, accommodation,convergence and pupil constriction tend to be linked. Pupil size alsocorrelates with the level of illumination. It is known that the pupilconstricts in brighter light conditions. Identification of inequality ofpupil size between the two eyes may assist in the detection ofpathology. Aniscoria (unequal pupil size) can be physiological or can berelated to abnormalities in the optic nerve or in the other cranialnerves that innervate the eye.

A health care practitioner can then consider information as to workingdistance 22, font size and status as to whether glasses are worn or notas well as other considerations in evaluating a user or a patient'sability to function when utilizing near vision. Various embodiments ofsystems, devices, and methods have been described herein.

These embodiments are given only by way of example and are not intendedto limit the scope of the claimed inventions. It should be appreciated,moreover, that the various features of the embodiments that have beendescribed may be combined in various ways to produce numerous additionalembodiments. Moreover, while various materials, dimensions, shapes,configurations and locations, etc. have been described for use withdisclosed embodiments, others besides those disclosed may be utilizedwithout exceeding the scope of the claimed inventions.

Persons of ordinary skill in the relevant arts will recognize that thesubject matter hereof may comprise fewer features than illustrated inany individual embodiment described above. The embodiments describedherein are not meant to be an exhaustive presentation of the ways inwhich the various features of the subject matter hereof may be combined.Accordingly, the embodiments are not mutually exclusive combinations offeatures; rather, the various embodiments can comprise a combination ofdifferent individual features selected from different individualembodiments, as understood by persons of ordinary skill in the art.Moreover, elements described with respect to one embodiment can beimplemented in other embodiments even when not described in suchembodiments unless otherwise noted.

Although a dependent claim may refer in the claims to a specificcombination with one or more other claims, other embodiments can alsoinclude a combination of the dependent claim with the subject matter ofeach other dependent claim or a combination of one or more features withother dependent or independent claims. Such combinations are proposedherein unless it is stated that a specific combination is not intended.

Any incorporation by reference of documents above is limited such thatno subject matter is incorporated that is contrary to the explicitdisclosure herein. Any incorporation by reference of documents above isfurther limited such that no claims included in the documents areincorporated by reference herein. Any incorporation by reference ofdocuments above is yet further limited such that any definitionsprovided in the documents are not incorporated by reference hereinunless expressly included herein.

For purposes of interpreting the claims, it is expressly intended thatthe provisions of 35 U.S.C. § 112(f) are not to be invoked unless thespecific terms “means for” or “step for” are recited in a claim.

1. A computer implemented method of assessing reading ability of a user,comprising: presenting a reading stimulus to patient on a display of ahandheld digital device; determining a working distance between thehandheld digital device and eyes of the user; and saving at least theworking distance determined to memory, reporting out the determinedworking distance on the display or both.
 2. The computer implementedmethod as claimed in claim 1, further comprising calibrating a processorof the handheld digital device by capturing an image of eye structures,facial structures or both while including an object of known size in thecaptured image.
 3. The computer implemented method as claimed in claim2, further comprising determining a size of the eye structures, facialstructures or both relative to the object of known size in the capturedimage.
 4. The computer implemented method as claimed in claim 1, furthercomprising determining the working distance directly or on the basis ofcomparison to the object of known size.
 5. The computer implementedmethod as claimed in claim 1, further comprising making a record of fontsize of letters on the display of the handheld digital device,brightness of the display or both.
 6. The computer implemented method asclaimed in claim 3, further comprising determining the working distancewhile reading material is read based on the previously determined sizeof eye structures or facial structures.
 7. The computer implementedmethod as claimed in claim 5, further comprising transmitting theworking distance and font size to a health care practitioner.
 8. Thecomputer implemented method as claimed in claim 1, further comprisinganalyzing a captured image of the user to determine if corrective lensesare worn at a time of the determination of working distance.
 9. Thecomputer implemented method as claimed in claim 8, further comprisingrecording status as to whether the corrective lenses are worn andtransmitting the status as to whether corrective lenses are a worn to ahealth care practitioner.
 10. The computer implemented method as claimedin claim 1, further comprising analyzing a captured image to determine apupil size; and optionally, transmit information of the pupil size to ahealth care practitioner.
 11. The computer implemented method as claimedin claim 1, further comprising presenting an optokinetic stimulus ofmoving bars, stripes or a checkerboard on the display of the handhelddigital device; and capturing moving images of eye movements that occurin response to the optokinetic stimulus.
 12. The computer implementedmethod as claimed in claim 11, further comprising analyzing the movingimages of eye movements in response to the optokinetic stimulus; and,optionally, transmitting the moving image of eye movements, the analysisof eye movements or both to a health care practitioner.
 13. The computerimplemented method as claimed in claim 1, further comprising measuringthe working distance by a depth mapping process using projected patternsincluding projecting an illuminated pattern of multiple spots onto theface of the user.
 14. The computer implemented method as claimed inclaim 1, further comprising creating a depth map of the user's faceincluding a matrix of pixels wherein each pixel corresponds torespective location on the face and includes a respective pixel valueindicative of a distance from a reference location at the handhelddigital device to respective location pixel.
 15. The computerimplemented method as claimed in claim 14, further comprising using thedepth map to identify a contour of the user's face representing theusers eyes or a bridge of a user's nose to determine a distance betweenthe users eyes or the users bridge of the nose and the handheld digitaldevice.
 16. The computer implemented method as claimed in claim 14,further comprising receiving color image data at a first input portincluding a first array of color image pixels from a first image sensor;receiving depth related image data at a second input port from a secondimage sensor and processing the depth related image data to generate adepth map.
 17. A handheld digital device, comprising: a display; acamera; a processor; and a memory; wherein the processor is in operablecommunication with the display, the camera and the memory and furthercomprises an image capture engine and an image analysis engine; theimage capture engine being programmed to execute the following:capturing an image of a user's face and eyes while the user is readingtext displayed on the display; and the image analysis engine beingprogrammed to execute the following: determining a working distancebetween the display and the user's eyes.
 18. The handheld digital deviceas claimed in claim 17, further wherein the image analysis engine isfurther programmed to use an apparent size of structures of users faceand eyes; and to calculate the working distance between display and theuser's eyes from the apparent size.
 19. The handheld digital device asclaimed in claim 17, further wherein the image analysis engine isfurther programmed to save additional information to memory selectedfrom a group consisting of time, date, lighting conditions, displaybrightness, pupil size, whether the user is wearing corrective lenses atthe time of recording and a combination of the foregoing.
 20. Thehandheld digital device as claimed in claim 17, further wherein theimage analysis engine is programmed to measure working distance by adepth mapping process using projected patterns including projecting anilluminated pattern of multiple spots onto the face of the user.
 21. Thehandheld digital device as claimed in claim 17, further wherein theimage analysis engine is programmed to create a depth map of the user'sface including a matrix of pixels wherein each pixel corresponds torespective location on the face and includes a respective pixel valueindicative of a distance from a reference location at the handhelddigital device to respective location pixel.
 22. The handheld digitaldevice as claimed in claim 21 further wherein the image analysis engineis programmed to analyze the depth map to identify a contourrepresenting the users eyes or a bridge of a user's nose to determine adistance between the users eyes or the users bridge of the nose and thehandheld digital device.
 23. The handheld digital device as claimed inclaim 17, further comprising apparatus for three dimensional mapping ofthe face that includes an illumination assembly having a coherent lightsource and a diffuser which are arranged to project an illuminatedspeckle pattern on the user's face; and wherein the camera comprises aninfrared sensor adapted to capture images of the illuminated specklepattern from a single location and at a known angular position relativeto the assembly.
 24. The handheld digital device as claimed in claim 23,wherein the image capture engine further comprises a first input portthe receives color image data and thus including a first array of colorimage pixels from a first image sensor and a second port the receivesdepth related image data from a second image sensor and processingcircuitry that generates a depth map using the depth related image data.